gford - 2:13 pm on Feb 24, 2011 (gmt 0)
I am still analyzing results but it almost smells like link age is a factor. Older more established pages SERPs seem to be benefiting. My newer pages with new links that ranked well seemed to have been hit.
Also your sites authority/trust seems to be a factor but I do have some really strong authority sites that lost rankings also.
So its a mixed bag and still trying to figure it out.